It is known that orthodontia currently uses devices known as brackets, which are bonded to the external face of the teeth and are integrally joined by a metal wire that exerts elastic strains, making it possible to adjust the relative positions of the teeth involved.
Such brackets are at present made of stainless steel or of a nickel/chromium alloy, which makes them unattractive because they are quite visible when they are applied to the teeth.
It is also known to make these brackets with the aid of transparent plastic materials, but these materials chemically degrade after a very short period of use, and do not have sufficient mechanical rigidity.
It has also been proposed that brackets be made of sintered alumina, but such brackets are fragile and have a high production cost.